Only warn about whitespace in section names

The warnings were logged even when the fix_section_name function was used
to fix non-section names.

server/core/service.cc

@@ -1142,7 +1142,7 @@ serviceSetFilters(SERVICE *service, char *filters)
     ptr = strtok_r(filters, "|", &brkt);
     while (ptr)
     {
-        fix_section_name(ptr);
+        fix_object_name(ptr);
 
         n++;
         MXS_FILTER_DEF **tmp;